class Solution {
    public int solution(int[] B) {  
        // write your code in Java SE 8  
        long[] rightToLeft = new long[A.length];  
        long[] leftToRight = new long[A.length];
        long[] A = new long[B.length]; 
        int result = -1;
    
        // Convert int array to long array
        int j = 0;  
        for (int value : B) {  
            A[j++] = (long)value;
        }  
        
        for(int i=0; i<rightToLeft.length; i++){  
            if(i==0){  
                rightToLeft[i] = A[i];  
            } else {  
                rightToLeft[i] = A[i] + rightToLeft[i-1];  
            }  
        }  
    
        for(int i=leftToRight.length-1; i>=0; i--){  
            if(i==leftToRight.length-1){  
                leftToRight[i] = A[i];  
            } else {  
                leftToRight[i] = A[i] + leftToRight[i+1];  
            }  
        }  
        
        for(int i=0; i<rightToLeft.length; i++){  
            if(rightToLeft[i] == leftToRight[i]) {  
                result = i;  
                break;  
            }  
        }  
        return result;  
    }  
}